Quantitative computed tomography analysis of local chemotherapy in liver tissue after radiofrequency ablation

RATIONALE AND OBJECTIVES: Computed tomography (CT) was used to noninvasively monitor local drug pharmacokinetics from polymer implants in rat livers before and following radiofrequency ablation. MATERIALS AND METHODS: Polymer matrixes containing carboplatin (a platinum-containing chemotherapeutic agent) were implanted into rat livers either immediately after radiofrequency ablation (n = 15) or without prior treatment (n = 15). The animals were divided into five subgroups (n = 3 per group) and subjected to a terminal CT scan at 6, 24, 48, 96, or 144 hours. Carboplatin concentration in tissue and within the implant matrix was correlated with CT intensity, and standard curves were produced for each environment. This correlation was used to evaluate the differences in drug transport properties between normal and ablated rat livers. A quantitative image analysis method was developed and used to evaluate the release rate and tissue distribution of carboplatin in normal and ablated liver tissue. The CT data were validated by previously reported atomic absorption spectroscopy measurement of implant and tissue drug levels. RESULTS: Correlation of carboplatin concentration and Hounsfield units results in a linear relationship with correlation coefficients (slopes) of 15 and 4 Hounsfield units/(mg/mL), for carboplatin in tissue and polymer, respectively. Noninvasive monitoring of local pharmacokinetics in normal and ablated tissues indicates that ablation before local carboplatin delivery increases the retention of carboplatin within the polymer matrix and drastically increases the drug retention in the ablated tissue volume (over 3-fold difference) resulting in a higher average dose to the surrounding tissue. At 1.6 mm from the implant boundary, carboplatin concentration is significantly higher in ablated tissue at 48, 96, and 144 hours (P <.05), and reaches 4.7 mg/mL in ablated tissue at 48 hours. In comparison, the concentration in normal liver at 1.6 mm reaches only 0.7 mg/mL at the same time point. The drug penetrates 3.1 mm in ablated liver compared with 2.3 mm in normal liver also at 48 hours. After 144 hours, the drug is still detected at 3.1 mm in ablated liver but not in normal liver. The differences are significant (P <.05) at both 48 and 144 hours. Correlation with chemical analysis suggests that CT data accurately predicts the drug pharmacokinetics in both ablated and normal livers. CONCLUSION: This work shows that X-ray CT imaging is a useful and promising technique for in vivo monitoring of the release kinetics of locally delivered radiopaque agents.     

Revealing in-stent stenoses of the iliac arteries: comparison of multidetector CT with MR angiography and digital radiographic angiography in a Phantom model

OBJECTIVE: Our objective was to evaluate the detectability of in-stent stenoses in iliac artery stents using multidetector CT angiography in comparison with MR angiography and digital radiographic angiography. MATERIALS AND METHODS: Ten different metallic stents (made of steel, nitinol, tantalum, or cobalt) were implanted in plastic tubes (8 mm). The stent lumina were partially obstructed by wax (CT density, -30 H) resulting in 50-60% in-stent stenoses. The tubes were filled with diluted contrast material (25 mmol/L of gadopentetate dimeglumine or 6 mg I/mL of iodinated contrast material) and placed in a plastic container filled with oil or water, respectively. CT angiography was performed on a four-detector CT scanner (detector collimation, 4 x 1 mm; slice thickness, 1.25 mm; table feed, 4 mm per rotation). MR angiography was performed on a 1.5-T system with a three-dimensional gradient-echo sequence (TR/TE, 4.6/1.8; flip angle, 30 degrees; slice thickness, 1.88 mm). Axial and longitudinal reformations of CT and MR imaging data were evaluated regarding the in-stent attenuation and signal intensity, the visible lumen diameter inside the stent, and the delineation of the stenoses. For comparison, digital radiographic angiography was performed as the gold standard. RESULTS: The degree and character of stent-related artifacts differed in CT angiography and MR angiography. In CT angiography, only the tantalum stent caused artifacts that obscured the stenosis; in all other cases, the stenoses were visible. In MR angiography, depiction of stenoses was impaired in two steel stents but possible in the tantalum and most nitinol stents. CONCLUSION: CT angiography is suited for detection of relevant stenoses in steel, cobalt-based, and nitinol stents. MR angiography is superior only in tantalum products.     

Experimentally induced small-bowel tumor in rabbits: US-guided percutaneous 18-gauge core biopsy

PURPOSE: To evaluate the safety and diagnostic yield of percutaneous 18-gauge core biopsy for an experimentally induced small-bowel tumor in a rabbit model. MATERIALS AND METHODS: Small-bowel tumors were induced by injecting VX2 tumor into 20 rabbits. After 3 weeks, the small bowel was filled with 100 mL of 2% diluted contrast agent containing methylene blue by using a 5-F catheter. Fifty biopsy firings for small-bowel tumor were performed with ultrasonographic (US) guidance by using an 18-gauge automatic gun. Computed tomography (CT) was performed before and immediately after biopsy. Any procedure-related complications, including leakage of air or fluid, hematoma, and perforation as seen at CT and identified at laparotomy, which was performed 48 hours after biopsy, were evaluated. White blood cell (WBC), red blood cell, and platelet counts; hemoglobin and hematocrit levels; and erythrocyte sedimentation rate were also obtained before and 48 hours after biopsy. Comparison was performed with paired t test. The diagnostic yield was calculated, and the specimen was evaluated whether fragments of mucosa were included or not. RESULTS: No contrast agent leakage or pneumoperitoneum suggesting perforation was identified at CT or laparotomy. Fluid leakage was observed with manual squeezing at two biopsy sites (4%). In two rabbits, hemoperitoneum was observed at CT or laparotomy. Hematoma larger than 3 cm was observed in six rabbits. WBC count and erythrocyte sedimentation rate slightly increased, and red blood cells, hemoglobin, hematocrit, and platelets counts had decreased slightly after biopsy but were not significant (P >.05). Definitive histologic diagnosis of tumor was obtained in 44 (88%) of 50 biopsy sites. Fragments of mucosa were observed in 13 (28%) specimens of 10 rabbits. CONCLUSION: Core biopsies of small-bowel tumor can be performed safely with an 18-gauge gun without severe complications and allow histologic diagnosis of small-bowel tumor with a good diagnostic yield.     

Improved coronary artery stent visualization and in-stent stenosis detection using 16-slice computed-tomography and dedicated image reconstruction technique

OBJECTIVE: The aim of this study was to compare the visualization of different coronary artery stents and the detectability of in-stent stenoses during 4-slice and 16-slice computed tomography (CT) angiography in a vessel phantom. MATERIAL AND METHODS: Ten coronary stents were introduced in a coronary artery vessel phantom (plastic tubes with an inner diameter of 3 mm, filled with iodinated contrast material diluted to 220 Hounsfiled Units [HU], surrounded by oil [60 HU]). CT scans were obtained perpendicular to the stent axes on a 4-slice scanner (detector collimation 4x1 mm; table feed 1.5 mm/rotation, mAs 300, kV 120, medium-smooth kernel) and a 16-slice scanner (detector collimation 12x0.75 mm; table feed 2.8 mm/rotation, mAs 370, kV 120, reconstruction with a standard and an optimized sharp kernel). Longitudinal multiplanar reformations were evaluated regarding visible lumen diameters and intraluminal attenuation values. Additionally, the stents were scanned with the same parameters after implantation of 60% stenoses (HU 30). RESULTS: Using the same medium-smooth kernel reconstruction with 4-slice and 16-slice CT, there was a slight increase in the average visible lumen area (26% versus 31%) and less increase of average intraluminal attenuation values (380 HU versus 349 HU). Significant improvement of lumen visualization (54%, P<0.01) and attenuation values (250, P<0.01) was observed for the 16-slice scans using the sharp kernel reconstruction. In-stent stenoses could be more reliably identified (or ruled out) by 16-slice CT and sharp reconstruction kernel when compared with the other 2 methods. CONCLUSION: 16-slice CT using a dedicated sharp kernel for image reconstruction facilitates improved visualization of coronary artery stent lumen and detection of in-stent stenoses.     

肝细胞癌合并胆管癌栓的CT表现与病理对照分析

目的分析肝细胞癌(hepatocellular carcinoma,HCC)合并胆管癌栓的CT及病理表现,以提高影像诊断准确性。资料与方法回顾性分析9例HCC合并胆管癌栓的临床、CT及病理表现。结果9例均在术前CT检查中发现HCC及胆管癌栓病灶。在CT像上肝内肿瘤呈现典型HCC表现。胆管癌栓在CT像上表现为扩张的胆管内填充有软组织块影,呈条索状或柱状,胆管远段扩张,胆管壁无增厚及肿瘤侵犯,在动脉期胆管癌栓呈现早期强化,无延迟强化改变。9例中有2例合并有门静脉癌栓。9例中低分化HCC8例,分化较好1例。胆管癌栓在显微镜下其细胞形态与肝内肿瘤原发灶相似。结论HCC合并胆管癌栓的CT表现有一定特点,CT对病灶的检出及定性诊断具有重要价值。     

肝细胞癌合并胆管癌栓的影像表现

目的 探讨胆管癌栓的影像表现,以提高影像诊断水平.方法 回顾性分析经手术病理证实的肝细胞癌(HCC)胆管癌栓13例患者资料,其中3例进行了CT和MR检查,2例仅行CT检查,8例仅行MR检查,7例进行了MR胰胆管成像检查,13例均进行了超声检查.采用四格表Fisher 确切概率检验方法比较超声与CT、MR诊断HCC胆管癌栓的准确性.结果 13例HCC肿瘤及胆管癌栓均在CT或MRI上显示.4例胆管癌栓在CT上表现为胆管内软组织块影,动脉期可见癌栓轻度增强,癌栓远端胆管扩张.11例胆管癌栓在T1 WI上均呈稍低信号,T2 WI为稍高信号,增强后可见轻、中度强化.MR胰胆管成像上胆管癌栓表现为:胆管阻塞中断、狭窄或不规则充盈缺损伴有梗阻上方胆管扩张,胆管突然截断或呈"鼠尾"状(5例);肝内胆管扩张,癌栓充满整个胆总管.胆总管不显示(2例).超声检查准确诊断胆管癌栓7例,误、漏诊6例.CT、MRI准确诊断12例,误诊4例,超声与CT、MRI诊断胆管癌栓差异无统计学意义(P=0.270).结论 CT或MRI对诊断HCC合并胆管癌栓及明确癌栓范围有价值.     

Semi-automatic measurement of the airway dimension by computed tomography using the full-width-half-maximum method: a study on the measurement accuracy according to the CT parameters and size of the airway.

OBJECTIVE: To assess the influence of variable factors such as the size of the airway and the CT imaging parameters such as the reconstruction kernel, field-of-view (FOV), and slice thickness on the automatic measurement of airway dimension. MATERIALS AND METHODS: An airway phantom was fabricated that contained eleven poly-acryl tubes of various lumen diameters and wall thicknesses. The measured density of the poly-acryl wall was 150 HU, and the measured density of the airspace filled with polyurethane foam was -900 HU. CT images were obtained using a 16-MDCT (multidetector CT) scanner and were reconstructed with various reconstruction kernels, thicknesses and FOV. The luminal radius and wall thickness were measured using in-house software based on the full-width-half-maximum method. The measured values as determined by CT and the actual dimensions of the tubes were compared. RESULTS: Measurements were most accurate on images reconstructed with use of a standard kernel (mean error: -0.03 +/- 0.21 mm for wall thickness and -0.12 +/- 0.11 mm for the luminal radius). There was no significant difference in accuracy among images with the use of variable slice thicknesses or a variable FOV. Below a 1-mm threshold, the measurement failed to represent the change of the real dimensions. CONCLUSION: Measurement accuracy was strongly influenced by the specific reconstruction kernel utilized. For accurate measurement, standardization of the imaging protocol and selection of the appropriate anatomic level are essential.     

Postpneumonectomy pulmonary artery stump thrombosis: CT features and imaging follow-up

PURPOSE: To retrospectively evaluate the computed tomographic (CT) features of pulmonary artery stump thrombosis at initial and follow-up CT. MATERIALS AND METHODS: The study was approved by institutional review board, which waived informed consent, and was HIPPA compliant. All patients who had undergone pneumonectomy and CT from January 2001 to August 2003, as identified with data search system, were included. Eighty-nine patients (49 men, 40 women; mean age, 60 years) were studied. Thrombus identification, categorization (concave or convex), and stump and thrombus measurements were made by two radiologists in consensus. The use of anticoagulation therapy was determined from patients' charts. The t test was used. RESULTS: Initial CT scans were obtained 34 months +/- 67 (standard deviation) after pneumonectomy; multiple CT scans were obtained in 58 patients during follow-up of 25.1 months +/- 24.8. Eleven (12.4%) of 89 patients had stump thrombi with near equal frequency on either side. Five concave and six convex thrombi were initially identified. Anticoagulation was not commenced for stump thrombosis. The mean length of the right stump (31 mm +/- 10) was greater than that of the left stump (13 mm +/- 7) (P < .01). After a right and left pneumonectomy, there was a significant difference between the length of the stump in patients with (right, 40 mm +/- 14; left, 21 mm +/- 11) and patients without thrombosis (right, 30 mm +/- 9; left, 12 mm +/- 6) (P = .027 and P < .01, respectively). Follow-up CT scans were not available in four cases. CT findings demonstrated a reduction in thrombus size in four patients (one received anticoagulation therapy for concomitant pulmonary embolism). Two patients had stable concave thrombi, one with an initial concave thrombus developed convex thrombus, and one with an initial convex thrombus developed concave thrombus. No thrombi propagated outside of the stump. CONCLUSION: There is a relationship between stump length and the development of in situ thrombosis. The data suggest a rather benign natural history.     

In vitro coronary artery imaging with sixteen-slice helical computed tomography

Purpose: To determine the benefits of submillimeter coronary computed tomography (CT) angiography in vitro.

Material and Methods: The coronary arteries of three domestic pigs were filled with contrast agent and depicted with clinically applicable CT angiography protocols with a slice thickness of 0.63 to 2.5 mm.

Results: With 2.5 mm slices, only the third-degree coronary artery branches could be discerned. With 1.25 mm slices, some fourth-degree branches of the right coronary artery could be discerned upon maximum intensity projections. With 0.63 mm slices, fourth-degree coronary artery branches could be discerned in all locations.

Conclusion: The introduction of 16-row detector CT with submillimeter z-axis resolution translates into an order-of-magnitude benefit for the depiction of coronary artery branches.     

CT of a bronchial phantom. Factors affecting appearance and size measurements

In order to determine the most appropriate window settings for viewing CT of the bronchial tree, we performed CT of a bronchial phantom consisting of air-filled tubes measuring from 3.1 to 12.7 mm, oriented at varying angles relative to the scan plane, surrounded by water or air, and with scan collimation of 10 mm, 5 mm, and 1.5 mm. Using a computer program to graphically display CT number relative to the distance across the tube's lumen, it was found that a window mean of -150 H accurately estimated the internal diameter of tubes surrounded by water, at all angles, when collimation was 5 mm or 1.5 mm. With 10-mm collimation, tube diameter was slightly underestimated for tubes 9.5 mm or less when oriented 30 degrees or more from perpendicular to the plane of scan. At lower window settings and window widths of 500 H or less, all tube's diameters were significantly underestimated. At -150 H, with tubes parallel to and centered in the scan plane, 5-mm and 1.5-mm collimation were most accurate; with decentering of 4 mm, 10-mm collimation better showed the tube's lumen. When surrounded by air, tube wall thickness was best estimated using a window mean of -450 H.     

MR detection of intracranial calcification: a phantom study

To make a comparative analysis of calcium detection between MR and CT, anhydrous, insoluble calcium carbonate spheres varying in size from 1.5-7.0 mm were embedded in three physiologic tissue phantoms: low-protein gelatin (3 gm%), high-protein gelatin (6 gm%), and heavy mineral oil. The calcium-containing phantoms were scanned by CT and MR, using both T1- and T2-weighted sequences, with a slice thickness varying from 5-7 mm. Partial volume artifacts were determined by abutting phantoms with and without calcium and by varying the slice position to include different proportions of the calcium- and noncalcium-containing phantoms. Contrast-detail curves, expressed as a ratio of contrast to noise, were determined for varying sizes of calcification and degrees of partial voluming. As expected, the CT conspicuity of calcification (positive contrast) markedly surpasses that of MR (negative contrast). The difference was two orders of magnitude. When the calcification filled more than half the slice on MR, the conspicuity depended on the contrast of the matrix material; i.e., increased matrix intensity caused increased conspicuity. However, as the size of the calcification decreased, partial volume effects increased; i.e., increased matrix intensity caused decreased conspicuity. Conspicuity of small calcifications is independent of matrix material, since contrast and partial volume effects balance. We conclude that CT is clearly the method of choice for identifying small foci of calcification.     

Multislice CT virtual intravascular endoscopy for abdominal aortic aneurysm stent grafts

PURPOSE: To investigate the optimal scanning protocols of multislice computed tomographic (CT) angiography in aortic stent graft placement observed on virtual intravascular endoscopy (VIE). MATERIALS AND METHODS: A human aorta phantom was built with a commercial aortic stent graft placed in situ. The phantom was housed in a perspex container and filled with contrast medium with CT attenuation similar to that used in the patient's abdominal scanning. CT was performed with a four-slice multislice CT scanner with section thickness of 1.3 mm, 2 mm, and 3.2 mm, pitch of 0.75, 1, and 1.5, and reconstruction interval of 50% overlap and no overlap. Stair-step artifacts were quantified by measuring the SD of signal intensity on surfaced shaded VIE images in three different locations: superior mesenteric artery (SMA), renal ostium, and aortic aneurysm. RESULTS: Image quality of VIE images was independent of section thickness and pitch values in the level of renal ostium and aortic aneurysm (P >.05), whereas it was determined by the section thickness and pitch in the level of SMA (P <.05). Aortic branch origin became irregular or distorted when section thickness increased to 3.2 mm or pitch reached 1.5. CONCLUSION: A scanning protocol of section thickness of 2 mm, pitch 1, and reconstruction interval of 1 mm is recommended in aortic stent graft placement because it allows fewer stair-step artifacts and better visualization of the aortic stent wires observed on VIE.     

Dose reduction in multidetector CT of the urinary tract. Studies in a phantom model

A novel ureter phantom was developed for investigations of image quality and dose in CT urography. The ureter phantom consisted of a water box (14 cm×32 cm×42 cm) with five parallel plastic tubes (diameter 2.7 mm) filled with different concentrations of contrast media (1.88–30 mg iodine/ml). CT density of the tubes and noise of the surrounding water were determined using two multidetector scanners (Philips MX8000 with four rows, Siemens Sensation 16 with 16 rows) with varying tube current–time product (15–100 mAs per slice), voltage (90 kV, 100 kV, 120 kV), pitch (0.875–1.75), and slice thickness (1 mm, 2 mm, 3.2 mm). Contrast-to-noise ratio as a parameter of image quality was correlated with dose (CTDI) and was compared with image evaluation by two radiologists. The CT densities of different concentrations of contrast media and contrast-to-noise ratio were significantly higher when low voltages (90 kV versus 120 kV, 100 kV versus 120 kV) were applied. Smaller slice thickness (1 mm versus 2 mm) did not change CT density but decreased contrast-to-noise ratio due to increased noise. Contrast phantom studies showed favourable effects of low tube voltage on image quality in the low dose range. This may facilitate substantial dose reduction in CT urography.     

Experimental venous thrombi: MRI characteristics with histopathological correlation

Objectives: The purpose of this study was to evaluate the MRI characteristics of venous thrombus over set time thresholds with histopathological correlation in a porcine model. Methods: Inferior vena cava thrombi were induced in 12 pigs. MRI was performed in three pigs 2 h, 1 day, 3 days and 2 weeks after thrombus induction. Results: The MRI characteristics were analysed in correlation with histopathological findings. The thrombi after 2 hours, which consisted of red blood cells (RBCs), showed isointensity on T(1 )weighted images (T(1)WIs) and hyperintensity on both T(2 )weighted images (T(2)WIs) and diffusion-weighted images (DWIs). The mean apparent diffusion coefficient (ADC) value was 1.93 × 10(-3) mm(2) s(-1). The thrombi after Day 1, which consisted of RBCs and migrating neutrophils at the periphery, showed isointensity on T(1)WIs, slight hyperintensity on T(2)WIs and hypointensity on DWIs. The mean ADC value was 1.62 × 10(-3) mm(2) s(-1) [corrected]. The thrombi after Day 3, which consisted of RBCs and peripheral inflammatory cells including macrophages, showed isointensity with peripheral hyperintense regions on T(1)WIs and hypointensity on both T(2)WIs and DWIs. The mean ADC value was 1.67 × 10(-3) mm(2) s(-1). After 2 weeks, the thrombi, which revealed RBC lysis surrounded by granulation tissues, showed isointensity on T(1)WIs and hyperintensity on T(2)WIs and DWIs. The mean ADC value was 2.48 × 10(-3) mm(2) s(-1). Conclusion: The temporal MRI characteristics seemed to be related to chemical and physical changes in RBC and organisation of granulation tissues. Free radicals generated by macrophages might also be related to some extent.     

Comparison of electron-beam and ungated helical CT in detecting coronary arterial calcification by using a working heart phantom and artificial coronary arteries

PURPOSE: To determine the sensitivity and specificity of cardiac gated electron-beam computed tomography (CT) and ungated helical CT in detecting and quantifying coronary arterial calcification (CAC) by using a working heart phantom and artificial coronary arteries. MATERIALS AND METHODS: A working heart phantom simulating normal cardiac motion and providing attenuation equal to that of an adult thorax was used. Thirty tubes with a 3-mm inner diameter were internally coated with pulverized human cortical bone mixed with epoxy glue to simulate minimal (n = 10), mild (n = 10), or severe (n = 10) calcified plaques. Ten additional tubes were not coated and served as normal controls. The tubes were attached to the same location on the phantom heart and scanned with electron-beam CT and helical CT in horizontal and vertical planes. Actual plaque calcium content was subsequently quantified with atopic spectroscopy. Two blinded experienced radiologic imaging teams, one for each CT system, separately measured calcium content in the model vessels by using a Hounsfield unit threshold of 130 or greater. RESULTS: The sensitivity and specificity of electron-beam CT in detecting CAC were 66.1% and 80.0%, respectively. The sensitivity and specificity of helical CT were 96.4% and 95.0%, respectively. Electron-beam CT was less reliable when vessels were oriented vertically (sensitivity and specificity, 71.4% and 70%; 95% CI: 39.0%, 75.0%) versus horizontally (sensitivity and specificity, 60.7% and 90.0%; 95% CI: 48.0%, 82.0%). When a correction factor was applied, the volume of calcified plaque was statistically better quantified with helical CT than with electron-beam CT (P =.004). CONCLUSION: Ungated helical CT depicts coronary arterial calcium better than does gated electron-beam CT. When appropriate correction factors are applied, helical CT is superior to electron-beam CT in quantifying coronary arterial calcium. Although further work must be done to optimize helical CT grading systems and scanning protocols, the data of this study demonstrated helical CT's inherent advantage over currently commercially available electron-beam CT systems in CAC detection and quantification.     

Hyperattenuating aortic wall on postmortem computed tomography (PMCT)

PURPOSE: To quantitatively evaluate the finding of hyperattenuating aortic wall on postmortem computed tomography (PMCT) and investigate its causes. MATERIALS AND METHODS: Our subjects were 50 PMCT of non-traumatic deaths and 50 CT of living persons (live CT). The ascending aorta at the level of the carina was visually assessed regarding the presence or absence of hyperattanuating aortic wall and hematocrit effect on PMCT and live CT. The diameter, thickness of the aortic wall, and CT number (HU) of the aortic wall and the lumen were also measured. RESULTS: Hyperattenuating aortic wall was detected in 100% of PMCT and 2% of live CT. The diameter of the aortic wall was 2.9 +/- 0.5 cm on PMCT and 3.5 +/- 0.5 cm on live CT, showing a significant difference. The thickness of the aortic wall was 2 mm on PMCT. Hematocrit effect was observed in 46% of PMCT and in none of live CT. With PMCT, there was a significant difference between the CT numbers of the upper and lower half portions of the lumen (19.6 +/- 11.7/30.9 +/- 12.9), whereas, with live CT, there was no such significant difference (37.4 +/- 7.6/38.9 +/- 6.7), with the overall value of 38.2 +/- 6.7. The CT number of the aortic wall was 49.9 +/- 10.9 on PMCT. CONCLUSION: The causes of hyperattenuating aortic wall on PMCT are considered to be increased attenuation due to contraction of the aortic wall, a lack of motion artifact, and decreased attenuation of the lumen due to dilution of blood after massive infusion at the time of cardiopulmonary resuscitation.     

Extension of radiofrequency ablation of the liver by transcatheter arterial embolization with iodized oil and gelatin sponge: results in a pig model

PURPOSE: To determine whether transcatheter arterial embolization (TAE) with iodized oil and gelatin sponge particles can be used to expand radiofrequency (RF)-induced coagulation necrosis, the morphology and histologic characteristics of ablation lesions were evaluated in the normal pig liver after three different TAE procedures. MATERIALS AND METHODS: Ten consecutive animals with 33 ablation lesions produced with an RF ablation system were randomly assigned to one of three treatment groups and a control group: a group treated with TAE with iodized oil, a group treated with TAE with gelatin sponge, a group treated with TAE with iodized oil and gelatin sponge, and a control group in which TAE was not performed. After the completion of ablation, the lesions were excised for gross and histologic examination. RESULTS: The longest and shortest diameters of ablation lesions were greatest in the group treated with TAE with iodized oil and gelatin sponge, followed by the groups treated with TAE with gelatin sponge and TAE with iodized oil (P < .05 vs controls, respectively). The hemorrhagic rim was also widest in the group treated with TAE with iodized oil and gelatin sponge (P < .05 vs controls), and it spread toward the liver periphery like a segmental hemorrhagic area adjacent to the ablation lesion. Histochemical staining for lactate dehydrogenase, maleate dehydrogenase, and nicotinamide adenine dinucleotide diaphorase showed what appeared to be 100% cellular destruction in all the ablation lesions and their hemorrhagic rims. CONCLUSION: RF ablation combined with TAE with iodized oil and gelatin sponge induces the greatest area of coagulation necrosis accompanied by peripherally spreading segmental necrosis in normal pig liver tissue.     

Relationship between various patterns of transient increased hepatic attenuation on CT and portal vein thrombosis related to acute cholecystitis

OBJECTIVE: We sought to investigate the prevalence of portal vein thrombosis in patients with acute cholecystitis and the relationship between portal vein thrombosis and the various patterns of transient increased hepatic attenuation on CT. MATERIALS AND METHODS: We studied 72 of 107 patients with acute cholecystitis who, during a 3-year period, underwent dual-phase contrast-enhanced CT before percutaneous cholecystostomy or cholecystectomy. CT scans were retrospectively reviewed for the presence of portal vein thrombosis and location of the thrombi and for patterns of transient increased hepatic attenuation, which were classified as either pericholecystic, segmental, or mixed. RESULTS: Portal vein thrombi (two in hepatic segment IV, three in the left portal vein, and one in the right posterior portal vein) were found in six (8.3%) of 72 patients, and in those patients, transient increased attenuation with a segmental (five patients) or mixed (one patient) pattern was seen on CT. The pattern of transient increased attenuation in the 54 patients without portal vein thrombosis was pericholecystic in 41 (75.9%) and mixed in 13 (24.1%). Nineteen patients had segmental distribution (segmental or mixed pattern) that in 31.6% (6/19) of the patients was associated with portal vein thrombosis. Segmental distribution was more frequently found in those patients who had acute cholecystitis with portal vein thrombosis than in those who had only acute cholecystitis (p = 0.001). CONCLUSION: In patients with acute cholecystitis, portal vein thrombosis is not uncommon. Patterns of transient increased hepatic attenuation were found to vary, depending on the presence or absence of portal vein thrombosis.     

Arterial wall imaging: evaluation with 16-section multidetector CT in blood vessel phantoms and ex vivo coronary arteries

PURPOSE: To evaluate the diagnostic performance of 16-section multidetector computed tomography (CT) for assessment of plaques in phantoms and ex vivo coronary arteries, with intravascular ultrasonography (US) and optical coherence tomography (OCT) as reference standards. MATERIALS AND METHODS: Research protocol was HIPAA compliant and approved by institutional review board, without informed consent required. Blood vessel and lesion composition phantoms and ex vivo coronary arteries were imaged with 16-section CT. Wall areas of phantoms and ex vivo coronary arteries were measured with multidetector CT and intravascular US. Sensitivity and specificity for lipid detection were determined in lesion composition phantoms. CT numbers of blood vessel wall were determined in ex vivo coronary arteries and compared with lesion classification results from OCT. Agreement in dimensional measurements was compared (paired t tests). CT numbers within blood vessel wall of CT cross sections classified as lipid rich, fibrous, and calcified at OCT were compared (Kruskal-Wallis tests). RESULTS: Mean blood vessel wall areas measured with CT and US in phantoms were 9.2 mm(2) +/- 1.8 (standard deviation) and 10.4 mm(2) +/- 3.4 (bias, -1.3 mm(2) +/- 3.1; P < .05), respectively. Mean blood vessel wall areas measured in ex vivo coronary arteries with CT and US were 10.9 mm(2) +/- 4.1 and 9.1 mm(2) +/- 3.1 (bias, 1.8 mm(2) +/- 3.0; P < .001), respectively. Sensitivity and specificity of 93% and 92%, respectively, for identification of lipid-rich lesions were observed in lesion composition phantoms. Mean CT numbers in blood vessel wall of ex vivo coronary arteries identified at OCT as predominantly lipid rich, fibrous, and calcified were 29 HU +/- 43, 101 HU +/- 21, and 135 HU +/- 199, respectively (P < .001). CONCLUSION: Determination of composition of individual plaques from attenuation values can be more challenging because of overlapping values for different tissue types.     

CT扫描对脊柱结核早期诊断的意义

目的:评价CT在脊柱结核早期诊断中的应用价值。材料与方法:10例早期脊柱结核患者,其中男性7例,女性3例,年龄为5～30岁,平均25岁,于发病后5个月至1年内经CT扫描后确诊。结果:CT扫描1、能清晰显示椎体的微小骨质破坏、死骨的大小与数目,以及死骨周围干酪样物的形成状况2、可清晰显示椎间盘的破坏程度、及相邻间盘及椎体软骨板的破坏状况,3、还可较早地发现双侧或单侧肿胀的腰大肌、腰小肌、髂腰肌及其脓肿等。CT确诊脊柱结核的中心型6例,边缘型3例,混合型1例。结论:CT可以显示X线上所不能显示的种种微小病变,它是脊柱结核早期诊断的重要工具。